In wireless communication systems that are based on 3G and 4G principles such as Long Term Evolution, an uplink channel and a downlink channel are separated by a guard band. The guard band is designed to be sufficiently large enough (e.g., >2× the channel bandwidth) so that interference caused by transmissions on the uplink and the downlink channels to receivers deployed in those channels is reduced to acceptable levels or below required levels that avoid significantly degrading their operation. A receiver on one channel becomes desensed when interference power in time and frequency from a nearby transmitter on another channel exceeds the ability of the receiver to reject that interference. The receiver can reject interference that is at low enough levels such that they do not impair receiver functions. Thus, the receiver has the ability to properly decode control signals and packet transmissions. With carrier aggregation, a wireless carrier has access to additional frequency spectrum that can be used for either the uplink or the downlink channels. By using the additional frequency spectrum as either the uplink or the downlink channels, the guard band can be reduced.
This reduction can increase the interference during transmissions of signals on the uplink or downlink channels. At least in those situations when transmissions on the uplink or downlink channels occur simultaneously and near or proximate, in terms of geographical as well as RF location and frequency, to receivers operating in corresponding channels adjacent to the uplink or downlink channels used for transmission, the interference may desense the user equipment and network equipment receivers operating in the adjacent channels such that it is difficult to decode signals on the control channel or the shared (data) channel. To achieve greater spectrum efficiency of existing allocated transmission bandwidth configurations and the additional configurations that are used as channels for various radio access technologies, the interference causing the desense issue needs to be reduced
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